/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina;

import java.beans.PropertyChangeListener;
import java.io.IOException;

/**
 * A <b>Store</b> is the abstraction of a Catalina component that provides
 * persistent storage and loading of Sessions and their associated user data.
 * Implementations are free to save and load the Sessions to any media they
 * wish, but it is assumed that saved Sessions are persistent across
 * server or context restarts.
 *
 * @author Craig R. McClanahan
 */
public interface Store {


	// ------------------------------------------------------------- Properties

	/**
	 * Return descriptive information about this Store implementation and
	 * the corresponding version number, in the format
	 * <code>&lt;description&gt;/&lt;version&gt;</code>.
	 */
	public String getInfo();

	/**
	 * Return the Manager instance associated with this Store.
	 */
	public Manager getManager();

	/**
	 * Set the Manager associated with this Store.
	 *
	 * @param manager The Manager which will use this Store.
	 */
	public void setManager(Manager manager);

	/**
	 * Return the number of Sessions present in this Store.
	 *
	 * @throws IOException if an input/output error occurs
	 */
	public int getSize() throws IOException;


	// --------------------------------------------------------- Public Methods

	/**
	 * Add a property change listener to this component.
	 *
	 * @param listener The listener to add
	 */
	public void addPropertyChangeListener(PropertyChangeListener listener);

	/**
	 * Return an array containing the session identifiers of all Sessions
	 * currently saved in this Store.  If there are no such Sessions, a
	 * zero-length array is returned.
	 *
	 * @throws IOException if an input/output error occurred
	 */
	public String[] keys() throws IOException;

	/**
	 * Load and return the Session associated with the specified session
	 * identifier from this Store, without removing it.  If there is no
	 * such stored Session, return <code>null</code>.
	 *
	 * @param id Session identifier of the session to load
	 * @throws ClassNotFoundException if a deserialization error occurs
	 * @throws IOException            if an input/output error occurs
	 */
	public Session load(String id)
			throws ClassNotFoundException, IOException;

	/**
	 * Remove the Session with the specified session identifier from
	 * this Store, if present.  If no such Session is present, this method
	 * takes no action.
	 *
	 * @param id Session identifier of the Session to be removed
	 * @throws IOException if an input/output error occurs
	 */
	public void remove(String id) throws IOException;

	/**
	 * Remove all Sessions from this Store.
	 */
	public void clear() throws IOException;

	/**
	 * Remove a property change listener from this component.
	 *
	 * @param listener The listener to remove
	 */
	public void removePropertyChangeListener(PropertyChangeListener listener);

	/**
	 * Save the specified Session into this Store.  Any previously saved
	 * information for the associated session identifier is replaced.
	 *
	 * @param session Session to be saved
	 * @throws IOException if an input/output error occurs
	 */
	public void save(Session session) throws IOException;


}
